Tropylium perchlorate, reaction with

The reaction of 2,4,6-trihalophenols with tropylium perchlorates in the presence of triethylamine gives phenolate dye (Scheme 10) followed by acetylation to give dye 76 from which the leuco compounds 77 can be prepared103 by catalytic reduction using Pd-C/H2. 

An index for predicting the reaction course of intramolecular photochemical cyclization of cycloheptatrienes and tropones, based upon the LCAO coefficients at the reaction sites of the HOMO S and LUMO s of the excited states, has been developed. The n.m.r. spectrum of the 8,9-benzobicyclo[5,2,0]nonatetraenyl anion (118) shows the presence of bond fixation and a preference for the dimethyl-enecyclobutene form. ° The rates of one-electron reduction of cyclopropyl-substituted tropylium perchlorates by chromous ion are consistent with the cyclopropyl group preferring a bisected conformation. ... 

Thiophen Analogues of Tropylium Ions and Related Compounds.—Condensation of 3,4-diformyl-2,5-dimethylthiophen with acetone or diethyl ketone yields the tropone (496). The reaction with acetone differs from that of phthalaldehyde, which only yields indanones." The reduction of (496) with LiAlH, and also the reaction with Grignard reagents, gave ethereal solutions of alcohols, which with HCIO4 gave the deep-blue tropylium-type perchlorates (497), which are stable in acetic acid." " The carbonium ion (497 R = Me) is less stable than the tropylium ion itself, as a mixture of (498 R = Me) and (499 R = Me) is obtained upon reaction with cyclo-... 

The calorimetric method was applied by Bowyer et al. (1971) to the polymerisation of N-vinyl carbazole (NVC) by tropylium hexafluoroantimonate and perchlorate in CH2C12 at 0 °C and -25 °C. The reactions were very fast and the reaction curves had a monotonically decreasing rate from the start. The initial reaction rate, R0, was correlated with the initiator and monomer concentrations by the equation... 

The photo-oxidation of the aryl-substituted cycloheptatrienes 7-(/ -methoxy-phenyl)cycloheptatriene and 7-, 1- and 3-(/ -dimethylaminophenyl)cycloheptatrienes to the corresponding radical cations in de-aerated acetonitrile solution was accomplished by electron transfer to the electronically excited acceptors 9,10-dicyanoanthracene, iV-methylquinolinium perchlorate, iV-methylacridinium perchlorate and l,T-dimethyl-4,4-bipyridinium dichloride. In the case of l- p-methoxyphenyl)cycloheptatriene (62), deprotonation of the radical cation occurs successfully, compared with back electron transfer, to give a cycloheptatrienyl radical (63) which undergoes a self-reaction forming a bitropyl. If the photooxidation is done in air-saturated acetonitrile solution containing HBF4 and one of the acceptors, the tropylium cation is formed. Back electron transfer dominates in the / -dimethylaminocycloheptatrienes and the formation of the cycloheptatrienyl radical is prevented. 

Tropylium aryltetrahalotellurates can be prepared from tropylium bromide and an aryl tellurium trihalide. A more convenient procedure avoiding the laborious preparation of the tropylium bromide uses cycloheptatriene and triphenylmethyl perchlorate. The product of this reaction can then be converted to the tetrahalotellurate by treatment with hydrohalic acids. 

Hydride abstraction. Dauben et al. prepared tropylium salts by reaction of cycloheptatriene with trityl perchlorate or fluoroborate in solution in acetonitrile or liquid sulfur dioxide at —20°. The reaction was of service also for the synthesis of heptalene (6). ... 

Reactions of the Alkyl Groups in Alkyltropylium Salts. Alkyl groups attached to tropylium rings are somewhat activated towards electrophilic attack. Thus in the presence of acetic anhydride orthoformic ester reacts with methyltropylium perchlorate to give the deep blue salt (XXIV) eind with 1,2-dimethyltropylium tetrafluoroborate to give the azulenium salt (XXV) [94]. 

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